Maximizing the total power with which a radio transmitter transmits a signal (not to be confused with the power levels with which the transmitter transmits individual channels carried by the signal) generally improves the transmitter's downlink capacity. Improved downlink capacity in this regard yields not only an increase in the number of users served by the radio transmitter, but also an increase in the throughput provided to each user.
Maximizing the transmitter's total transmit power must nonetheless be balanced against complying with various performance metric thresholds specified for the transmitted signal. For example, requirements that limit the signal's spectral emissions and targets that specify expectations for the signal's quality prove more difficult to comply with as the transmitter's total transmit power increases (with a corresponding increase in transmitter temperature). Radio transmitters must therefore be designed to control their maximum transmit power to balance downlink capacity improvement against signal performance.
Known radio transmitters are designed to control their maximum transmit power in this way by comparing the current transmitter temperature to temperature thresholds. For example, if the current transmitter temperature reaches or exceeds a first threshold, a transmitter backs off (i.e., derates) its maximum transmit power in order to remain in compliance with defined performance metric thresholds. And if the current transmitter temperature reaches or exceeds a second, higher threshold, the transmitter shuts down one or more of its components in order to protect transmitter hardware.
These temperature thresholds are established universally for an entire class of radio transmitters during the transmitter design phase. This design phase entails analyzing the signal performance of a few test transmitters under worst-case operating conditions and determining the temperature thresholds at which those test transmitters should adjust their maximum transmit power in order to comply with defined performance metric thresholds. This analysis is then extrapolated to all transmitters in the class by adding in margins to the determined thresholds, resulting in universal worst-case thresholds that will guarantee all transmitters in the class comply with the defined performance metric thresholds.
Sub-component device variations across the transmitters in the class, though, mean that the universal worst-case thresholds overly stifle the potential performance of at least some of the transmitters in the class. These stifled transmitters, for example, may actually be able to transmit at higher maximum power (or at the same maximum power for a longer amount of time) and still comply with the performance metric thresholds, but are artificially limited to transmitting at a lower maximum power (or at the same maximum power for a shorter amount of time) because of the universal and worst-case nature of the thresholds.